libnetlink.c

   1 /*
   2  * libnetlink.c RTnetlink service routines.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <syslog.h>
  17 #include <fcntl.h>
  18 #include <net/if_arp.h>
  19 #include <sys/socket.h>
  20 #include <netinet/in.h>
  21 #include <string.h>
  22 #include <errno.h>
  23 #include <time.h>
  24 #include <sys/uio.h>
  25
  26 #include "libnetlink.h"
  27
  28 void rtnl_close(struct rtnl_handle *rth)
  29 {
  30         close(rth->fd);
  31 }
  32
  33 int rtnl_open_byproto(struct rtnl_handle *rth, unsigned subscriptions,
  34                       int protocol)
  35 {
  36         socklen_t addr_len;
  37         int sndbuf = 32768;
  38         int rcvbuf = 32768;
  39
  40         memset(rth, 0, sizeof(rth));
  41
  42         rth->fd = socket(AF_NETLINK, SOCK_RAW, protocol);
  43         if (rth->fd < 0) {
  44                 perror("Cannot open netlink socket");
  45                 return -1;
  46         }
  47
  48         if (setsockopt(rth->fd, SOL_SOCKET, SO_SNDBUF, &sndbuf, sizeof(sndbuf))
  49             < 0) {
  50                 perror("SO_SNDBUF");
  51                 return -1;
  52         }
  53
  54         if (setsockopt(rth->fd, SOL_SOCKET, SO_RCVBUF, &rcvbuf, sizeof(rcvbuf))
  55             < 0) {
  56                 perror("SO_RCVBUF");
  57                 return -1;
  58         }
  59
  60         memset(&rth->local, 0, sizeof(rth->local));
  61         rth->local.nl_family = AF_NETLINK;
  62         rth->local.nl_groups = subscriptions;
  63
  64         if (bind(rth->fd, (struct sockaddr *)&rth->local, sizeof(rth->local)) <
  65             0) {
  66                 perror("Cannot bind netlink socket");
  67                 return -1;
  68         }
  69         addr_len = sizeof(rth->local);
  70         if (getsockname(rth->fd, (struct sockaddr *)&rth->local, &addr_len) < 0) {
  71                 perror("Cannot getsockname");
  72                 return -1;
  73         }
  74         if (addr_len != sizeof(rth->local)) {
  75                 fprintf(stderr, "Wrong address length %d\n", addr_len);
  76                 return -1;
  77         }
  78         if (rth->local.nl_family != AF_NETLINK) {
  79                 fprintf(stderr, "Wrong address family %d\n",
  80                         rth->local.nl_family);
  81                 return -1;
  82         }
  83         rth->seq = time(NULL);
  84         return 0;
  85 }
  86
  87 int rtnl_open(struct rtnl_handle *rth, unsigned subscriptions)
  88 {
  89         return rtnl_open_byproto(rth, subscriptions, NETLINK_ROUTE);
  90 }
  91
  92 int rtnl_wilddump_request(struct rtnl_handle *rth, int family, int type)
  93 {
  94         struct {
  95                 struct nlmsghdr nlh;
  96                 struct rtgenmsg g;
  97         } req;
  98         struct sockaddr_nl nladdr;
  99
 100         memset(&nladdr, 0, sizeof(nladdr));
 101         nladdr.nl_family = AF_NETLINK;
 102
 103         memset(&req, 0, sizeof(req));
 104         req.nlh.nlmsg_len = sizeof(req);
 105         req.nlh.nlmsg_type = type;
 106         req.nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
 107         req.nlh.nlmsg_pid = 0;
 108         req.nlh.nlmsg_seq = rth->dump = ++rth->seq;
 109         req.g.rtgen_family = family;
 110
 111         return sendto(rth->fd, (void *)&req, sizeof(req), 0,
 112                       (struct sockaddr *)&nladdr, sizeof(nladdr));
 113 }
 114
 115 int rtnl_send(struct rtnl_handle *rth, const char *buf, int len)
 116 {
 117         struct sockaddr_nl nladdr;
 118
 119         memset(&nladdr, 0, sizeof(nladdr));
 120         nladdr.nl_family = AF_NETLINK;
 121
 122         return sendto(rth->fd, buf, len, 0, (struct sockaddr *)&nladdr,
 123                       sizeof(nladdr));
 124 }
 125
 126 int rtnl_dump_request(struct rtnl_handle *rth, int type, void *req, int len)
 127 {
 128         struct nlmsghdr nlh;
 129         struct sockaddr_nl nladdr;
 130         struct iovec iov[2] = {
 131                 {.iov_base = &nlh,.iov_len = sizeof(nlh)}
 132                 ,
 133                 {.iov_base = req,.iov_len = len}
 134         };
 135         struct msghdr msg = {
 136                 .msg_name = &nladdr,
 137                 .msg_namelen = sizeof(nladdr),
 138                 .msg_iov = iov,
 139                 .msg_iovlen = 2,
 140         };
 141
 142         memset(&nladdr, 0, sizeof(nladdr));
 143         nladdr.nl_family = AF_NETLINK;
 144
 145         nlh.nlmsg_len = NLMSG_LENGTH(len);
 146         nlh.nlmsg_type = type;
 147         nlh.nlmsg_flags = NLM_F_ROOT | NLM_F_MATCH | NLM_F_REQUEST;
 148         nlh.nlmsg_pid = 0;
 149         nlh.nlmsg_seq = rth->dump = ++rth->seq;
 150
 151         return sendmsg(rth->fd, &msg, 0);
 152 }
 153
 154 int rtnl_dump_filter(struct rtnl_handle *rth,
 155                      rtnl_filter_t filter,
 156                      void *arg1, rtnl_filter_t junk, void *arg2)
 157 {
 158         struct sockaddr_nl nladdr;
 159         struct iovec iov;
 160         struct msghdr msg = {
 161                 .msg_name = &nladdr,
 162                 .msg_namelen = sizeof(nladdr),
 163                 .msg_iov = &iov,
 164                 .msg_iovlen = 1,
 165         };
 166         char buf[16384];
 167
 168         iov.iov_base = buf;
 169         while (1) {
 170                 int status;
 171                 struct nlmsghdr *h;
 172
 173                 iov.iov_len = sizeof(buf);
 174                 status = recvmsg(rth->fd, &msg, 0);
 175
 176                 if (status < 0) {
 177                         if (errno == EINTR)
 178                                 continue;
 179                         perror("OVERRUN");
 180                         continue;
 181                 }
 182
 183                 if (status == 0) {
 184                         fprintf(stderr, "EOF on netlink\n");
 185                         return -1;
 186                 }
 187
 188                 h = (struct nlmsghdr *)buf;
 189                 while (NLMSG_OK(h, status)) {
 190                         int err;
 191
 192                         if (nladdr.nl_pid != 0 ||
 193                             h->nlmsg_pid != rth->local.nl_pid ||
 194                             h->nlmsg_seq != rth->dump) {
 195                                 if (junk) {
 196                                         err = junk(&nladdr, h, arg2);
 197                                         if (err < 0)
 198                                                 return err;
 199                                 }
 200                                 goto skip_it;
 201                         }
 202
 203                         if (h->nlmsg_type == NLMSG_DONE)
 204                                 return 0;
 205                         if (h->nlmsg_type == NLMSG_ERROR) {
 206                                 struct nlmsgerr *err =
 207                                     (struct nlmsgerr *)NLMSG_DATA(h);
 208                                 if (h->nlmsg_len <
 209                                     NLMSG_LENGTH(sizeof(struct nlmsgerr))) {
 210                                         fprintf(stderr, "ERROR truncated\n");
 211                                 } else {
 212                                         errno = -err->error;
 213                                         perror("RTNETLINK answers");
 214                                 }
 215                                 return -1;
 216                         }
 217                         err = filter(&nladdr, h, arg1);
 218                         if (err < 0)
 219                                 return err;
 220
 221                       skip_it:
 222                         h = NLMSG_NEXT(h, status);
 223                 }
 224                 if (msg.msg_flags & MSG_TRUNC) {
 225                         fprintf(stderr, "Message truncated\n");
 226                         continue;
 227                 }
 228                 if (status) {
 229                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 230                         return -1;
 231                 }
 232         }
 233 }
 234
 235 int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n, pid_t peer,
 236               unsigned groups, struct nlmsghdr *answer,
 237               rtnl_filter_t junk, void *jarg)
 238 {
 239         int status;
 240         unsigned seq;
 241         struct nlmsghdr *h;
 242         struct sockaddr_nl nladdr;
 243         struct iovec iov = {
 244                 .iov_base = (void *)n,
 245                 .iov_len = n->nlmsg_len
 246         };
 247         struct msghdr msg = {
 248                 .msg_name = &nladdr,
 249                 .msg_namelen = sizeof(nladdr),
 250                 .msg_iov = &iov,
 251                 .msg_iovlen = 1,
 252         };
 253         char buf[16384];
 254
 255         memset(&nladdr, 0, sizeof(nladdr));
 256         nladdr.nl_family = AF_NETLINK;
 257         nladdr.nl_pid = peer;
 258         nladdr.nl_groups = groups;
 259
 260         n->nlmsg_seq = seq = ++rtnl->seq;
 261
 262         if (answer == NULL)
 263                 n->nlmsg_flags |= NLM_F_ACK;
 264
 265         status = sendmsg(rtnl->fd, &msg, 0);
 266
 267         if (status < 0) {
 268                 perror("Cannot talk to rtnetlink");
 269                 return -1;
 270         }
 271
 272         memset(buf, 0, sizeof(buf));
 273
 274         iov.iov_base = buf;
 275
 276         while (1) {
 277                 iov.iov_len = sizeof(buf);
 278                 status = recvmsg(rtnl->fd, &msg, 0);
 279
 280                 if (status < 0) {
 281                         if (errno == EINTR)
 282                                 continue;
 283                         perror("OVERRUN");
 284                         continue;
 285                 }
 286                 if (status == 0) {
 287                         fprintf(stderr, "EOF on netlink\n");
 288                         return -1;
 289                 }
 290                 if (msg.msg_namelen != sizeof(nladdr)) {
 291                         fprintf(stderr, "sender address length == %d\n",
 292                                 msg.msg_namelen);
 293                         return -1;
 294                 }
 295                 for (h = (struct nlmsghdr *)buf; status >= sizeof(*h);) {
 296                         int err;
 297                         int len = h->nlmsg_len;
 298                         int l = len - sizeof(*h);
 299
 300                         if (l < 0 || len > status) {
 301                                 if (msg.msg_flags & MSG_TRUNC) {
 302                                         fprintf(stderr, "Truncated message\n");
 303                                         return -1;
 304                                 }
 305                                 fprintf(stderr,
 306                                         "!!!malformed message: len=%d\n", len);
 307                                 return -1;
 308                         }
 309
 310                         if (nladdr.nl_pid != peer ||
 311                             h->nlmsg_pid != rtnl->local.nl_pid ||
 312                             h->nlmsg_seq != seq) {
 313                                 if (junk) {
 314                                         err = junk(&nladdr, h, jarg);
 315                                         if (err < 0)
 316                                                 return err;
 317                                 }
 318                                 /* Don't forget to skip that message. */
 319                                 status -= NLMSG_ALIGN(len);
 320                                 h = (struct nlmsghdr *)((char *)h +
 321                                                         NLMSG_ALIGN(len));
 322                                 continue;
 323                         }
 324
 325                         if (h->nlmsg_type == NLMSG_ERROR) {
 326                                 struct nlmsgerr *err =
 327                                     (struct nlmsgerr *)NLMSG_DATA(h);
 328                                 if (l < sizeof(struct nlmsgerr)) {
 329                                         fprintf(stderr, "ERROR truncated\n");
 330                                 } else {
 331                                         errno = -err->error;
 332                                         if (errno == 0) {
 333                                                 if (answer)
 334                                                         memcpy(answer, h,
 335                                                                h->nlmsg_len);
 336                                                 return 0;
 337                                         }
 338                                         perror("RTNETLINK answers");
 339                                 }
 340                                 return -1;
 341                         }
 342                         if (answer) {
 343                                 memcpy(answer, h, h->nlmsg_len);
 344                                 return 0;
 345                         }
 346
 347                         fprintf(stderr, "Unexpected reply!!!\n");
 348
 349                         status -= NLMSG_ALIGN(len);
 350                         h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
 351                 }
 352                 if (msg.msg_flags & MSG_TRUNC) {
 353                         fprintf(stderr, "Message truncated\n");
 354                         continue;
 355                 }
 356                 if (status) {
 357                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 358                         return -1;
 359                 }
 360         }
 361 }
 362
 363 int rtnl_listen(struct rtnl_handle *rtnl, rtnl_filter_t handler, void *jarg)
 364 {
 365         int status;
 366         struct nlmsghdr *h;
 367         struct sockaddr_nl nladdr;
 368         struct iovec iov;
 369         struct msghdr msg = {
 370                 .msg_name = &nladdr,
 371                 .msg_namelen = sizeof(nladdr),
 372                 .msg_iov = &iov,
 373                 .msg_iovlen = 1,
 374         };
 375         char buf[8192];
 376
 377         memset(&nladdr, 0, sizeof(nladdr));
 378         nladdr.nl_family = AF_NETLINK;
 379         nladdr.nl_pid = 0;
 380         nladdr.nl_groups = 0;
 381
 382         iov.iov_base = buf;
 383         while (1) {
 384                 iov.iov_len = sizeof(buf);
 385                 status = recvmsg(rtnl->fd, &msg, 0);
 386
 387                 if (status < 0) {
 388                         if (errno == EINTR)
 389                                 continue;
 390                         if (errno == EAGAIN)
 391                                 return 0;
 392                         perror("OVERRUN");
 393                         return -1;
 394                 }
 395                 if (status == 0) {
 396                         fprintf(stderr, "EOF on netlink\n");
 397                         return -1;
 398                 }
 399                 if (msg.msg_namelen != sizeof(nladdr)) {
 400                         fprintf(stderr, "Sender address length == %d\n",
 401                                 msg.msg_namelen);
 402                         return -1;
 403                 }
 404                 for (h = (struct nlmsghdr *)buf; status >= sizeof(*h);) {
 405                         int err;
 406                         int len = h->nlmsg_len;
 407                         int l = len - sizeof(*h);
 408
 409                         if (l < 0 || len > status) {
 410                                 if (msg.msg_flags & MSG_TRUNC) {
 411                                         fprintf(stderr, "Truncated message\n");
 412                                         return -1;
 413                                 }
 414                                 fprintf(stderr,
 415                                         "!!!malformed message: len=%d\n", len);
 416                                 return -1;
 417                         }
 418
 419                         err = handler(&nladdr, h, jarg);
 420                         if (err < 0) {
 421                                 fprintf(stderr, "Handler returned %d\n", err);
 422                                 return err;
 423                         }
 424
 425                         status -= NLMSG_ALIGN(len);
 426                         h = (struct nlmsghdr *)((char *)h + NLMSG_ALIGN(len));
 427                 }
 428                 if (msg.msg_flags & MSG_TRUNC) {
 429                         fprintf(stderr, "Message truncated\n");
 430                         continue;
 431                 }
 432                 if (status) {
 433                         fprintf(stderr, "!!!Remnant of size %d\n", status);
 434                         return -1;
 435                 }
 436         }
 437 }
 438
 439 int rtnl_from_file(FILE * rtnl, rtnl_filter_t handler, void *jarg)
 440 {
 441         int status;
 442         struct sockaddr_nl nladdr;
 443         char buf[8192];
 444         struct nlmsghdr *h = (void *)buf;
 445
 446         memset(&nladdr, 0, sizeof(nladdr));
 447         nladdr.nl_family = AF_NETLINK;
 448         nladdr.nl_pid = 0;
 449         nladdr.nl_groups = 0;
 450
 451         while (1) {
 452                 int err, len, type;
 453                 int l;
 454
 455                 status = fread(&buf, 1, sizeof(*h), rtnl);
 456
 457                 if (status < 0) {
 458                         if (errno == EINTR)
 459                                 continue;
 460                         perror("rtnl_from_file: fread");
 461                         return -1;
 462                 }
 463                 if (status == 0)
 464                         return 0;
 465
 466                 len = h->nlmsg_len;
 467                 type = h->nlmsg_type;
 468                 l = len - sizeof(*h);
 469
 470                 if (l < 0 || len > sizeof(buf)) {
 471                         fprintf(stderr, "!!!malformed message: len=%d @%lu\n",
 472                                 len, ftell(rtnl));
 473                         return -1;
 474                 }
 475
 476                 status = fread(NLMSG_DATA(h), 1, NLMSG_ALIGN(l), rtnl);
 477
 478                 if (status < 0) {
 479                         perror("rtnl_from_file: fread");
 480                         return -1;
 481                 }
 482                 if (status < l) {
 483                         fprintf(stderr, "rtnl-from_file: truncated message\n");
 484                         return -1;
 485                 }
 486
 487                 err = handler(&nladdr, h, jarg);
 488                 if (err < 0)
 489                         return err;
 490         }
 491 }
 492
 493 int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
 494 {
 495         int len = RTA_LENGTH(4);
 496         struct rtattr *rta;
 497         if (NLMSG_ALIGN(n->nlmsg_len) + len > maxlen) {
 498                 fprintf(stderr,
 499                         "addattr32: Error! max allowed bound %d exceeded\n",
 500                         maxlen);
 501                 return -1;
 502         }
 503         rta = NLMSG_TAIL(n);
 504         rta->rta_type = type;
 505         rta->rta_len = len;
 506         memcpy(RTA_DATA(rta), &data, 4);
 507         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;
 508         return 0;
 509 }
 510
 511 int addattr_l(struct nlmsghdr *n, int maxlen, int type, const void *data,
 512               int alen)
 513 {
 514         int len = RTA_LENGTH(alen);
 515         struct rtattr *rta;
 516
 517         if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) > maxlen) {
 518                 fprintf(stderr,
 519                         "addattr_l ERROR: message exceeded bound of %d\n",
 520                         maxlen);
 521                 return -1;
 522         }
 523         rta = NLMSG_TAIL(n);
 524         rta->rta_type = type;
 525         rta->rta_len = len;
 526         memcpy(RTA_DATA(rta), data, alen);
 527         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);
 528         return 0;
 529 }
 530
 531 int addraw_l(struct nlmsghdr *n, int maxlen, const void *data, int len)
 532 {
 533         if (NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len) > maxlen) {
 534                 fprintf(stderr,
 535                         "addraw_l ERROR: message exceeded bound of %d\n",
 536                         maxlen);
 537                 return -1;
 538         }
 539
 540         memcpy(NLMSG_TAIL(n), data, len);
 541         memset((void *)NLMSG_TAIL(n) + len, 0, NLMSG_ALIGN(len) - len);
 542         n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + NLMSG_ALIGN(len);
 543         return 0;
 544 }
 545
 546 int rta_addattr32(struct rtattr *rta, int maxlen, int type, __u32 data)
 547 {
 548         int len = RTA_LENGTH(4);
 549         struct rtattr *subrta;
 550
 551         if (RTA_ALIGN(rta->rta_len) + len > maxlen) {
 552                 fprintf(stderr,
 553                         "rta_addattr32: Error! max allowed bound %d exceeded\n",
 554                         maxlen);
 555                 return -1;
 556         }
 557         subrta = (struct rtattr *)(((char *)rta) + RTA_ALIGN(rta->rta_len));
 558         subrta->rta_type = type;
 559         subrta->rta_len = len;
 560         memcpy(RTA_DATA(subrta), &data, 4);
 561         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + len;
 562         return 0;
 563 }
 564
 565 int rta_addattr_l(struct rtattr *rta, int maxlen, int type,
 566                   const void *data, int alen)
 567 {
 568         struct rtattr *subrta;
 569         int len = RTA_LENGTH(alen);
 570
 571         if (RTA_ALIGN(rta->rta_len) + RTA_ALIGN(len) > maxlen) {
 572                 fprintf(stderr,
 573                         "rta_addattr_l: Error! max allowed bound %d exceeded\n",
 574                         maxlen);
 575                 return -1;
 576         }
 577         subrta = (struct rtattr *)(((char *)rta) + RTA_ALIGN(rta->rta_len));
 578         subrta->rta_type = type;
 579         subrta->rta_len = len;
 580         memcpy(RTA_DATA(subrta), data, alen);
 581         rta->rta_len = NLMSG_ALIGN(rta->rta_len) + RTA_ALIGN(len);
 582         return 0;
 583 }
 584
 585 int parse_rtattr(struct rtattr *tb[], int max, struct rtattr *rta, int len)
 586 {
 587         memset(tb, 0, sizeof(struct rtattr *) * (max + 1));
 588         while (RTA_OK(rta, len)) {
 589                 if (rta->rta_type <= max)
 590                         tb[rta->rta_type] = rta;
 591                 rta = RTA_NEXT(rta, len);
 592         }
 593         if (len)
 594                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len,
 595                         rta->rta_len);
 596         return 0;
 597 }
 598
 599 int parse_rtattr_byindex(struct rtattr *tb[], int max, struct rtattr *rta,
 600                          int len)
 601 {
 602         int i = 0;
 603
 604         memset(tb, 0, sizeof(struct rtattr *) * max);
 605         while (RTA_OK(rta, len)) {
 606                 if (rta->rta_type <= max && i < max)
 607                         tb[i++] = rta;
 608                 rta = RTA_NEXT(rta, len);
 609         }
 610         if (len)
 611                 fprintf(stderr, "!!!Deficit %d, rta_len=%d\n", len,
 612                         rta->rta_len);
 613         return i;
 614 }